An agricultural baler is known e.g. from EP 1 066 747. The agricultural baler described therein is provided with a plunger and a baling chamber, and is arranged for repeatedly forming bales by moving the plunger back and forth in the baling chamber. The agricultural baler is further provided with a pick-up system for picking up crop material from the field and a feeder system being arranged for repeatedly feeding a quantity of crop material towards the baling chamber such that the crop material can be pressed by the plunger in the baling chamber to form a bale.
In practice, there is a desire to produce bales of approximately uniform size and weight. Therefore, a quantity of the crop material that is repeatedly fed towards the baling chamber and that is pressed into a bale, preferably is approximately constant. However, there are several factors that may prevent the constant feeding of crop material to the baling chamber.
Firstly, the frequency of repetition of the plunger may be different from the frequency of repetition of the stuffer or a multiple thereof. Such a stuffer frequency may be approximately defined by a filling time of the feeding chamber. Thus, when the stuffer is ready for feeding a quantity of crop material towards the baling chamber, the plunger may be in an extended, pressing position instead of a retracted position. When the plunger is in the pressing position, it will close of the feed opening such that it is not possible to push crop material in the baling chamber. As a result, the stuffer needs to be delayed in order to wait for the plunger to be retracted and clearing the feed opening into the baling chamber. Experience showed that, as a result of such waiting, the amount of accumulated crop material which is stuffed into the baling chamber by one feed stroke changes. As a result, the quantity of crop material that is pressed into each slice of the bale may change as well. Thus, the resulting bale can have a size and/or weight that is different from the desired size and/or weight.
Secondly, the composition of the crop material may change during use of the agricultural baler, or in between different periods of use of the agricultural baler. The amount of crop material available on the field at specific locations on the field may vary due to e.g. lack of fertilisation or lower and wet land. Such change in composition may also lead to a change in composition of the crop material stuffed into the baling chamber, and hence to a change in a quantity of crop material pressed into a bale. Thus again, the resulting bale can have a size and/or weight that is different from the desired size and/or weight.